This invention pertains to the art of switches, and more particularly to make-before-break switches.
The invention is particularly applicable to a dimmer switch used to control headlights on an automotive vehicle in conjunction with a flash-to-pass or so-called silent horn, and will be described with particular reference thereto. However, it will be appreciated that the invention has broader applications and may be advantageously employed in other switching environments and applications.
Reference is made to U.S. Pat. No. 3,883,710 of Hanssen, et al. issued May 13, 1975 which is herein incorporated by reference and is directed to a predecessor dimmer switch. Although this switch mechanism has met with commercial success, selected portions of the switch, as will be noted below, are believed capable of further improvement. From a purely economic standpoint, the terminals as described in the Hanssen patent result in a high cost of manufacture due to tolerance, fit, and positioning problems as well as detailed handling during assembly. Although the switch is rather compact in nature, it necessarily includes a series of bends in the terminals which result in the tolerance and position problems. Each terminal has to be individually and selectively plated.
The wiper blades in the prior art switch of the Hanssen, et al. patent include three resilient arms designed to each contain their own spring load and bear against various portions of an electrical contact. Since each arm is resiliently biased with respect to the remainder of the wiper assembly, each wiper finger imposes its own spring load on the contact portions which leads to uneven contact forces and erosion failure. Further, each arm is difficult to manufacture to the required tolerance.
Assembly of the prior art switch requires insertion of a pre-installation pin for correct placement on the steering column. Without this pin, alignment of the switch is difficult to determine and results in improper forces and positioning of the dimmer switch.
The prior art actuator cap is disposed along the exterior of the switch body. Although having predetermined stop limit positions, the cap necessarily enlarges the overall size of the switch. The actuator cap is also subject to some limited wobble with respect to the body.
Lastly, the "feel" of the prior switch is described as mushy and lacking in a positive, crisp actuation. Further studies appear to indicate that the force/displacement curve of the switch does not illustrate the theoretical sharp decrease in the force past a detent position. Further, the stroke of the switch is considered too large.
The subject invention is deemed to provide an improved dimmer switch with flash-to-pass capabilities that overcomes all of the above-noted deficiencies in an economical manner.